Switching nodes are used in communications networks to switch and route data traffic between sources and destinations. A switching node typically receives data traffic in the form of data packets as input at interface ports (ingress of the node) and outputs the data packets as output at interface ports (egress of the node) to direct the data packets to an appropriate destination in the communications network. The switching nodes of a network may each include a clock to maintain local time at the node. The nodes maintain time synchronization through each node synchronizing as a slave node to a master node that maintains a master clock. The nodes synchronize by monitoring selected IP packets sent by the master node. The selected IP packets are time stamped with master clock time when sent from the master node and time stamped with slave clock time when received at the slave node. By knowing the transmission time delay between the master and slave nodes, a time correction value may be calculated at the slave node and the clock of the slave node may be corrected.
Certain protocols for synchronizing master and slave clocks of nodes in a network provide correction values generated at the slave node, the correction values themselves provide limited information. In network data monitoring centers, the information available only shows corrections generated at slave nodes. However, there is no procedure to auto-detect abnormal changes in the synchronization process that may indicate other problems in the network.